1. Field of the Invention
The present invention relates to a method of controlling an aircraft, missile, munition or ground vehicle with plasma actuators, and more particularly to controlling fluid flow across their surfaces or other surfaces, which would benefit from such a method. The method includes the design of an aerodynamic plasma actuator for the purpose of controlling airflow separation over a control surface of a aircraft, missile, or a ground vehicle, and more particularly to the method of determining a modulation frequency for the plasma actuator for the purpose of fluid flow control over these vehicles.
2. Technical Background
Traditionally aircraft, missiles, munitions or ground vehicles use conventional control surfaces to control or assist in controlling aerodynamic stability and/or maneuverability during operation. For example, high-lift systems play an important role in the design of air vehicles. The wings on most modern-day air vehicles are equipped with high-lift systems, generally in the form of leading-edge slats and trailing-edge flaps. These devices have been shown to enhance the aerodynamic performance of air vehicles through improvements in the coefficient of lift, lift to drag ratio, and stall-angle. Advantages of such performance-enhancing devices include improvements in maneuverability, turn rates, glide range and payload, and reductions in takeoff/landing distance and field length requirements. Another example of traditional control surfaces is the use of front and rear spoilers, inlets, wings and other control surfaces on ground vehicles.
While the benefits of these conventional types of control surfaces are well documented, it is also known that the use of movable control surfaces increase airframe noise and vibration, particularly at high deflection angles. With these types of surfaces, most of the noise originates from the separated flow in the gap or hinge regions which contribute to the drag component of the viscous drag on the control surface. At off design conditions, the drag penalty from these traditional control surfaces is very high. For example by some estimates used in wing and tail design, eliminating the hinge gaps would result in a 10% drag decrease. In addition, for military applications, the hinge gap is a source of radar wave reflection resulting in a more detectable radar image. Another drawback with traditional control surfaces is that motors or pneumatics are required, which add volume, weight, and costs to these types of systems.
In view of the foregoing disadvantages of presently available control surfaces, it is desirable to develop methods and flow control systems for missiles, aircraft, munitions and ground vehicles which overcome these limitations. Further it is desirable to develop methods and flow control systems that are hingeless and retain/improve the aerodynamic effects without compromising lift performance.